Sequence Settings Fix?

I'm working on a sequence that is set to 16:9. The elements are 4:3. I realized after creating the timeline that my settings for the sequence needed to be 4:3. Now when I change the settings to 4:3 the video looks blown up in the 4:3 window. Is there a way to change the settings for the sequence to 4:3 and keep the video correct in the 4:3 window?